With some prior art devices, letters of different formats and postcards are processed in a continuous item stream. In order to determine the postage or fees necessary for the processing, the weight of the individual items of mail is determined. The items of mail being guided over a weighing device for this purpose. Here, the item stream may not be retarded discernibly or even stopped. It is to be ensured in currently running systems that the weighing operation is carried out reliably despite high item streams of up to 50,000 items of mail per hour. The scales which have been used previously in the weighing devices are restricted in principle in their weighing frequency, however, since they first have to settle on the weighing device before they can weigh a new item of mail precisely. In addition, the apparatuses are also to be designed in such a way that the items of mail are not damaged at belt speeds of more than two meters per second. DE 196 04 090 A1 has disclosed an apparatus of the foregoing type for the automatic weight determination of items of mail, in which apparatus the transport section is apportioned at a distributor device into two or more parallel weighing sections, a set of scales being provided in each of the weighing sections, with the result that each set of scales has to manage only the corresponding part of the amount of items of mail. In this way, weighing operations can be performed with great precision on a continuous item stream at high speed. As a result of the fact that, for example, only every second item of mail from the input item stream has to be weighed by each set of scales, therefore the individual set of scales has more time to settle again after removal of the item of mail and to prepare itself for the next weighing operation. Here, the connection of the drives which is disclosed, in particular, in DE 196 04 090 A1 ensures that a displacement of the relative position of the items of mail with respect to one another in the item stream is avoided.
It is then one object of subject matter disclosed herein to optimize an apparatus with regard to its installation space and its flexibility, without impairing the precision of the weighing operations at high speed and density of the item stream. In addition, it is an object of subject matter disclosed herein to provide a weighing module which, with a particularly simple construction, makes it possible to extend the processing apparatuses for the purpose of a further increase in the throughput. There is a need to have independent weighing devices with a bypass means that are modular in design for placement at various locations in the mail transport path.
With other prior art devices, items of mail and, in particular, flat letters of different formats and postcards are processed in a continuous item stream. In order to determine the necessary postage or fees for the processing, the weight of the individual items of mail is determined, the items of mail being guided for this purpose via a weighing device. Here, the item stream must not be retarded appreciably or even stopped. Systems which are currently used can carry out weighing reliably at high item streams of up to 50,000 items of mail per hour. The scales which were previously used in the weighing devices are limited in their weighing frequency in principle, however, because they have to settle before they can weigh a new item of mail precisely. In addition, a certain overall length of the scales is necessary, in order to have the letter which is to be weighed on the scales for long enough and for it to be possible to carry out an accurate measurement. Finally, the measurement has to be finished in the known apparatuses before the letter is gripped by the guide belts of the discharge path which lead it away and the reference system of the scales is coupled to that of the surroundings.
It is therefore an object subject matter disclosed herein to provide an improved, technically simple means with regard to the precision of the weighing operations despite a high speed and density of the item stream.